In which type of breeding is there a higher possibility of the accumulation of harmful recessive genes?

Mule is an example of . . . . . . .

Which of the following is a cross-breed of sheep?

Cross breeding:
$I$. Refers to the cross of a superior male of one breed with a superior female of another breed.
$II$. It helps to accumulate the desirable genes of the two breeds into a progeny.
$III$. The progeny may be used for commercial production.
Which of the statements given above are correct?

The technique of cryopreservation is used for

What is a surrogate mother useful for?